FINAL SPECIES STATUS ASSESSMENT FOR THE PACIFIC WALRUS (Odobenus rosmarus divergens), May 2017 (Version 1.0) James G. MacCracken, William S. Beatty, Joel L. Garlich-Miller, Michelle L. Kissling, Jonathan A. Snyder U.S. Fish and Wildlife Service, Marine Mammals Management, 1011 E. Tudor Rd.MS-341, Anchorage, AK 99503 LIST OF ACRONYMS ADEC – Alaska Department of Environmental Conservation ADFG – Alaska Department of Fish and Game AK – Alaska BBN – Bayesian Belief Network BOEM – Bureau of Ocean Energy Management CACO3 – calcium carbonates CCR – calf:cow ratio CMIP – Coupled Model Intercomparison Project CO2 – carbon dioxide CPT – Conditional Probability Table ESA – Endangered Species Act EWC – Eskimo Walrus Commission GCM – Global (or General) Circulation Model GHG – Greenhouse Gas IPCC - Intergovernmental Panel on Climate Change ITR – Incidental Take Regulation LOA – Letter of Authorization LTK – local and traditional ecological knowledge MMPA – Marine Mammal Protection Act NSR – Northern Sea Route NWP – Northwest Passage OA – ocean acidification RCP – Representative Concentration Pathway SSA – Species Status Assessment SST – Sea Surface Temperature TEK – traditional ecological knowledge USFWS – US Fish and Wildlife Service USGS – US Geological Survey USSR – Union of Soviet Socialist Republics YBP – years before present ii iii CONTENTS List of Acronyms ............................................................................................................................................ ii Executive Summary ....................................................................................................................................... 8 1. Introduction .............................................................................................................................................. 9 1.1 Review of Previous Listing Actions ...................................................................................................... 9 1.2 Purpose of this Assessment .............................................................................................................. 10 2. Description of the Pacific Walrus ............................................................................................................ 11 2.1 Taxonomy .......................................................................................................................................... 12 2.2 Subspecies Description and Needs ................................................................................................... 14 2.2.1 Behavior ..................................................................................................................................... 14 2.2.2 Feeding and Prey ........................................................................................................................ 14 2.2.3 Seasonal Distributions................................................................................................................ 16 2.2.4 Habitat Use................................................................................................................................. 19 2.3 Vital Rates ......................................................................................................................................... 24 2.3.1 Reproduction and Productivity .................................................................................................. 24 2.4 Population Abundance and Trends ................................................................................................... 25 2.4.1 Population Modelling ................................................................................................................. 26 2.4.2 Population Indices ...................................................................................................................... 26 2.5 Adaptive Capacity of Pacific Walruses .............................................................................................. 29 2.5.1 Evolutionary History of the Pacific Walrus ................................................................................ 29 2.5.2 Behavioral Adaptation of Pacific Walruses ................................................................................ 30 2.5.3 Intrinsic Adaptive Capacity of Pacific Walruses ......................................................................... 31 3. Current Resource Conditions .................................................................................................................. 33 3.1 Marine Habitats ................................................................................................................................ 33 3.1.1. Sea Ice ....................................................................................................................................... 33 3.1.2 Annual Trends in Sea Ice ............................................................................................................ 35 3.1.3 Effects of Sea Ice Changes on Pacific Walruses ......................................................................... 36 3.1.4 Ocean Warming ......................................................................................................................... 36 3.1.5 Ocean and Benthic Productivity ................................................................................................. 37 3.1.6 Ocean Acidification .................................................................................................................... 40 3.2 Coastal Habitats ................................................................................................................................ 43 4 3.2.1 Use of Bristol Bay Haulouts ........................................................................................................ 43 3.2.2 Use of Chukchi Sea Haulouts ..................................................................................................... 43 3.2.3 Haulout Mortalities .................................................................................................................... 44 3.3 Harvest .............................................................................................................................................. 46 3.3.1 History of Harvest ...................................................................................................................... 47 3.3.2 Harvest Patterns ........................................................................................................................ 47 3.3.3 Harvest Sustainability................................................................................................................. 49 3.4 Disease and Parasites ........................................................................................................................ 50 3.4.1 Infectious Disease ...................................................................................................................... 50 3.4.2 Parasites ..................................................................................................................................... 51 3.5 Predation ........................................................................................................................................... 52 3.5.1 Polar Bears ................................................................................................................................. 52 3.5.2 Killer Whales .............................................................................................................................. 53 3.6 Contaminants and Biotoxins ............................................................................................................. 53 3.6.1. Persistent Organic Pollutants .................................................................................................... 54 3.6.2 Heavy Metals.............................................................................................................................. 54 3.6.3 Radionuclides ............................................................................................................................. 55 3.6.4 Biotoxins ..................................................................................................................................... 56 3.7 Oil and Gas Exploration, Development, and Production .................................................................. 56 3.8 Commercial Fisheries ........................................................................................................................ 60 3.9 Ship and Air Traffic ............................................................................................................................ 63 3.9.1 Shipping ...................................................................................................................................... 63 3.9.2 Air Traffic .................................................................................................................................... 68 3.10 Existing Regulatory Protections ...................................................................................................... 68 3.11 Local and Traditional Ecological Knowledge ................................................................................... 69 3.12 Resiliency, Representation, and Redundancy of the Pacific walrus ............................................... 72 3.12.1 Resiliency ................................................................................................................................